Hybrid vehicles (HEV) and electric vehicles (EV) use chargeable-dischargeable energy storages. Secondary batteries such as lithium ion batteries are typical energy storages for HEV and EV vehicles. Lithium ion secondary batteries typically use carbon, such as graphite, as the anode electrode. The automotive industry is continually developing means of improving the energy density of these batteries. For example, the use of thicker battery electrodes is being investigated as one means of increasing the battery's energy density. Thicker electrodes pose new challenges, such as difficulty with lithium ion diffusion through the thicker active materials.